Independent feeding and breathing skills are the two important functions for survival in human infants. Feeding difficulties coupled with airway-related complications in infants contribute significantly to infant mortality and morbidity. Lack of a proper understanding of the physiology and pathophysiology of reflexes protective against aspiration during health or disease in developing infants is a fundamental problem that challenges management strategies. Our long-term goal is to develop evidence-based safe feeding strategies in infants at-risk. The current objective is to define the normal development as a basis for understanding abnormality of the sensory-motor neural and muscular control of foregut motility and aerodigestive tract defense mechanisms in human infants. There is a critical need for safety-ensured mechanistic studies that will provide a solid foundation for the management of feeding and airway safety in (1) healthy premature infants and in conditions such as (2) GERD and (3) neurological disease. In aim 1, peristaltic reflexes induced by esophageal stimulation in preterm healthy infants in sleep and awake states are investigated. In aim 2, the relationship of GERD on reflux clearance- and glottal closure- reflexes and comparison with healthy controls are investigated. In aim 3, the effects of neurological malfunction on aerodigestive protective mechanisms and comparison with healthy controls are investigated. Using safety packed, cutting-edge techniques and micromanometry system and novel pharyngo-esophageal manometry catheters, synchronized and integrated respiratory measurements, we will evaluate the sensory and motor elements of the peristaltic reflexes in premature infants, GERD, and neurological illness. In addition, we will evaluate airway protective reflexes with concurrent ultrasound. ANOVA, multiple logistic regression and student's t- test will be used. The new information will create a context for understanding sensory-motor-pathways involved with peristaltic reflexes and airway safety;thus providing a basis for future clinical care or trials.